1. Field of the Invention
The present invention relates in general to devices or systems for providing a conductive path to ground to dissipate static charges that have accumulated on personnel who are involved in the repair or assembly of microelectronic devices. More particularly the invention relates to a conductive wrist strap which is connected by way of a conductor to a suitable means for making electrical contact with a ground station. The suitable means may take the form of an alligator clip or a banana plug.
2. The Prior Art
It is common practice in the electronics industry to take steps to assure that individuals who are involved in the assembly or repair of microelectronic components, such as memory devices, are free of electrostatic charge so as to avoid effective destruction of the devices when the individual contacts them. If the individual has accumulated an electrostatic charge, the contact with the device would cause a discharge and effectively destroy the electronic component. To this end there have appeared a number of wrist straps for grounding personnel at work stations to enable them to work on sensitive components sensitive to static charge. In one instance the wrist strap is comprised of a conductive polyester wrist strap with a Velcro type fastener.
Another example of prior art wrist straps is one wherein an all textile strap is impregnated with a thermosetting conductive coating and fastened about the wrist of an operator. In all instances the wrist strap is connected by way of a swivel type snap connector and insulated conductor to a suitable device for making a connection to ground at the work station.
While all purport to provide for easy disconnection of the operator in order to leave the work station, they have in fact proven to be difficult so that operators to avoid breaking fingernails have resorted merely to pulling on the conductive wire which after a number of disconnections is weakened and in many cases broken, thus impairing the effectiveness of the ground connection. In other instances there have been provided high resistance elements in series with the conductor for the purpose of providing a safety measure by reducing the flow of current to an operator should the wire insulation become worn or frayed and thereafter the hand come in contact with a source of high voltage. In some instances the resistor has been provided in series in the conductor near the end to be connected to the ground station which does not afford any protection whatsoever under the circumstances outlined above. And in other instances the resistor has been placed near the wrist of the operator but by reason of continued connection and disconnection has resulted in a broken contact thereby rendering the wrist strap ineffective.